25.10.2018

In a nutshell: Some highly interconnected areas of the brain are more vulnerable to disruption than others, which could explain how disorders such as schizophrenia develop.

In the human brain, billions of cells communicate with each other in networks – known as the human connectome – to carry out complex functions quickly and accurately.

Because of minor variations between individuals, our connectomes are not identical. This diversity can be good, because it helps the human population to adapt to changing environmental conditions. But too much variation – when an individual’s connectome is too far from ‘normal’ – can be bad. Abnormal brain connectivity has been linked to disorders such as schizophrenia.

Brain Function CoE investigators Leonardo Gollo, James Roberts and Michael Breakspear from QIMR Berghofer Medical Research Institute and their colleagues wanted to understand what happens when the connectome is altered too much.

The researchers used diffusion magnetic resonance imaging (MRI) – a non-invasive method for looking inside the brain – to map the connectome in a group of healthy volunteers. Using computational modelling, they randomly ‘rewired’, or rearranged, the connections within these maps. Then they examined how these changes affected hubs, the most interconnected areas within the network. Hubs are believed to be involved more often than other brain areas in disorders such as schizophrenia.

The researchers found that the most fragile hubs – the ones that became disconnected from the network most quickly as a result of rewiring – corresponded to the brain areas that degrade the fastest in people with schizophrenia. This finding suggests that some hubs may be more vulnerable to damage than other parts of the human connectome.

This knowledge could help researchers to understand what causes some people to develop schizophrenia and to identify people at risk of developing this disorder.

Next steps:The researchers are investigating how important the structure of the connectome is to the development of other neuropsychiatric diseases.